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| #include <cstdio>
#define inf 999999999
#define maxN 500010
#define maxM 1000010
struct nodea{ int h, v, q; } a[maxN];
struct nodeb{ int x, y, c, g; } b[maxM];
int color[maxN], dis[maxN], bj[maxN], f[maxN];
int last[maxN], ge[maxN], bh[maxN];
int len = 0, cnt = 0, n = 0, m = 0, L = 0;
int min (int x, int y)
{
return x < y ? x : y;
}
int max (int x, int y)
{
return x > y ? x : y;
}
int read ()
{
int x = 0;
char c = getchar();
while(c < '0' || c > '9')
{
c = getchar();
}
while(c >= '0' && c <= '9')
{
x = x * 10 + (c - '0');
c = getchar();
}
return x;
}
void ins (int x, int y, int c)
{
len++;
b[len].x = x;
b[len].y = y;
b[len].c = c;
b[len].g = a[x].h;
a[x].h = len;
}
void dfs (int x)
{
for(int i = a[x].h;i;i = b[i].g)
{
int y = b[i].y;
if(!color[y])
{
ge[++last[0]] = last[cnt];
bh[last[0]] = y;
last[cnt] = last[0];
color[y] = color[x];
dfs(y);
}
}
}
int bfs (int st, int flag)
{
for(int i = last[color[st]];i;i = ge[i])
{
int x = bh[i];
a[x].q = inf;
}
int tou = 1, wei = 2;
f[1] = st;
a[st].v = 1;
a[st].q = 0;
while(tou != wei)
{
int x = f[tou];
for(int i = a[x].h;i;i = b[i].g)
{
int y = b[i].y;
if(a[x].q + b[i].c < a[y].q)
{
a[y].q = a[x].q + b[i].c;
if(!a[y].v)
{
a[y].v = 1;
f[wei] = y;
wei++;
if(wei >= maxN)
{
wei = 1;
}
}
}
}
a[x].v = 0;
tou++;
if(tou >= maxN)
{
tou = 1;
}
}
for(int i = last[color[st]];i;i = ge[i])
{
int x = bh[i];
}
if(flag)
{
int ma = 0, wz = 0;
for(int i = last[color[st]];i;i = ge[i])
{
int x = bh[i];
if(a[x].q > ma)
{
wz = x;
ma = a[x].q;
}
}
return wz;
}
dis[st] = max(dis[st], a[st].q);
for(int i = last[color[st]];i;i = ge[i])
{
int x = bh[i];
dis[x] = max(dis[x], a[x].q);
}
return 0;
}
void px (int l, int r)
{
int x = l, y = r, mid = bj[(l + r) / 2];
while(x <= y)
{
while(bj[x] > mid)
{
x++;
}
while(bj[y] < mid)
{
y--;
}
if(x <= y)
{
int t = bj[x];
bj[x] = bj[y];
bj[y] = t;
x++;
y--;
}
}
if(l < y)
{
px(l, y);
}
if(x < r)
{
px(x, r);
}
}
int main ()
{
n = read();
m = read();
L = read();
for(int i = 1;i <= m; i++)
{
int x = 0, y = 0, c = 0;
x = read() + 1;
y = read() + 1;
c = read();
ins(x, y, c);
ins(y, x, c);
}
last[0] = 0;
for(int i = 1;i <= n; i++)
{
if(!color[i])
{
color[i] = ++cnt;
bh[++last[0]] = i;
last[cnt] = last[0];
dfs(i);
int X = bfs(i, 1);
int Y = bfs(X, 1);
bfs(X, 0);
bfs(Y, 0);
}
}
for(int i = 1;i <= cnt; i++)
{
bj[i] = 2147483647;
}
for(int i = 1;i <= n; i++)
{
if(dis[i] == inf)
{
dis[i] = 0;
}
bj[color[i]] = min(bj[color[i]], dis[i]);
}
px(1, cnt);
int ans = 0;
for(int i = 1;i <= n; i++)
{
ans = max(ans, dis[i]);
}
ans = max(ans, max(bj[1] + bj[2] + L, bj[2] + bj[3] + 2 * L));
printf("%d", ans);
return 0;
}
|